/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/

/**
 * \file cipher.c
 *
 * \brief Generic cipher wrapper for mbed TLS
 *
 * \author Adriaan de Jong <dejong@fox-it.com>
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#include "tls/config.h"

#if defined(MBEDTLS_CIPHER_C)

#include "tls/cipher.h"
#include "tls/cipher_internal.h"

#include <stdlib.h>
#include <string.h>

#if defined(MBEDTLS_GCM_C)
#include "tls/gcm.h"
#endif

#if defined(MBEDTLS_CCM_C)
#include "tls/ccm.h"
#endif

#if defined(MBEDTLS_CMAC_C)
#include "tls/cmac.h"
#endif

#if defined(MBEDTLS_PLATFORM_C)
#include "tls/platform.h"
#else
#define mbedtls_calloc calloc
#define mbedtls_free   free
#endif

#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
#define MBEDTLS_CIPHER_MODE_STREAM
#endif

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void *v, size_t n)
{
	volatile unsigned char *p = (unsigned char *)v;
	while (n--) {
		*p++ = 0;
	}
}

static int supported_init = 0;

const int *mbedtls_cipher_list(void)
{
	const mbedtls_cipher_definition_t *def;
	int *type;

	if (!supported_init) {
		def = mbedtls_cipher_definitions;
		type = mbedtls_cipher_supported;

		while (def->type != 0) {
			*type++ = (*def++).type;
		}

		*type = 0;

		supported_init = 1;
	}

	return (mbedtls_cipher_supported);
}

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_type(const mbedtls_cipher_type_t cipher_type)
{
	const mbedtls_cipher_definition_t *def;

	for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
		if (def->type == cipher_type) {
			return (def->info);
		}

	return (NULL);
}

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_string(const char *cipher_name)
{
	const mbedtls_cipher_definition_t *def;

	if (NULL == cipher_name) {
		return (NULL);
	}

	for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
		if (!strcmp(def->info->name, cipher_name)) {
			return (def->info);
		}

	return (NULL);
}

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_values(const mbedtls_cipher_id_t cipher_id, int key_bitlen, const mbedtls_cipher_mode_t mode)
{
	const mbedtls_cipher_definition_t *def;

	for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
		if (def->info->base->cipher == cipher_id && def->info->key_bitlen == (unsigned)key_bitlen && def->info->mode == mode) {
			return (def->info);
		}

	return (NULL);
}

void mbedtls_cipher_init(mbedtls_cipher_context_t *ctx)
{
	memset(ctx, 0, sizeof(mbedtls_cipher_context_t));
}

void mbedtls_cipher_free(mbedtls_cipher_context_t *ctx)
{
	if (ctx == NULL) {
		return;
	}
#if defined(MBEDTLS_CMAC_C)
	if (ctx->cmac_ctx) {
		mbedtls_zeroize(ctx->cmac_ctx, sizeof(mbedtls_cmac_context_t));
		mbedtls_free(ctx->cmac_ctx);
	}
#endif

	if (ctx->cipher_ctx) {
		ctx->cipher_info->base->ctx_free_func(ctx->cipher_ctx);
	}

	mbedtls_zeroize(ctx, sizeof(mbedtls_cipher_context_t));
}

int mbedtls_cipher_setup(mbedtls_cipher_context_t *ctx, const mbedtls_cipher_info_t *cipher_info)
{
	if (NULL == cipher_info || NULL == ctx) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	memset(ctx, 0, sizeof(mbedtls_cipher_context_t));

	if (NULL == (ctx->cipher_ctx = cipher_info->base->ctx_alloc_func())) {
		return (MBEDTLS_ERR_CIPHER_ALLOC_FAILED);
	}

	ctx->cipher_info = cipher_info;

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
	/*
	 * Ignore possible errors caused by a cipher mode that doesn't use padding
	 */
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
	(void)mbedtls_cipher_set_padding_mode(ctx, MBEDTLS_PADDING_PKCS7);
#else
	(void)mbedtls_cipher_set_padding_mode(ctx, MBEDTLS_PADDING_NONE);
#endif
#endif							/* MBEDTLS_CIPHER_MODE_WITH_PADDING */

	return (0);
}

int mbedtls_cipher_setkey(mbedtls_cipher_context_t *ctx, const unsigned char *key, int key_bitlen, const mbedtls_operation_t operation)
{
	if (NULL == ctx || NULL == ctx->cipher_info) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN) == 0 && (int)ctx->cipher_info->key_bitlen != key_bitlen) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	ctx->key_bitlen = key_bitlen;
	ctx->operation = operation;

	/*
	 * For CFB and CTR mode always use the encryption key schedule
	 */
	if (MBEDTLS_ENCRYPT == operation || MBEDTLS_MODE_CFB == ctx->cipher_info->mode || MBEDTLS_MODE_CTR == ctx->cipher_info->mode) {
		return ctx->cipher_info->base->setkey_enc_func(ctx->cipher_ctx, key, ctx->key_bitlen);
	}

	if (MBEDTLS_DECRYPT == operation) {
		return ctx->cipher_info->base->setkey_dec_func(ctx->cipher_ctx, key, ctx->key_bitlen);
	}

	return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
}

int mbedtls_cipher_set_iv(mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len)
{
	size_t actual_iv_size;

	if (NULL == ctx || NULL == ctx->cipher_info || NULL == iv) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	/* avoid buffer overflow in ctx->iv */
	if (iv_len > MBEDTLS_MAX_IV_LENGTH) {
		return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
	}

	if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_IV_LEN) != 0) {
		actual_iv_size = iv_len;
	} else {
		actual_iv_size = ctx->cipher_info->iv_size;

		/* avoid reading past the end of input buffer */
		if (actual_iv_size > iv_len) {
			return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
		}
	}

	memcpy(ctx->iv, iv, actual_iv_size);
	ctx->iv_size = actual_iv_size;

	return (0);
}

int mbedtls_cipher_reset(mbedtls_cipher_context_t *ctx)
{
	if (NULL == ctx || NULL == ctx->cipher_info) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	ctx->unprocessed_len = 0;

	return (0);
}

#if defined(MBEDTLS_GCM_C)
int mbedtls_cipher_update_ad(mbedtls_cipher_context_t *ctx, const unsigned char *ad, size_t ad_len)
{
	if (NULL == ctx || NULL == ctx->cipher_info) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
		return mbedtls_gcm_starts((mbedtls_gcm_context *) ctx->cipher_ctx, ctx->operation, ctx->iv, ctx->iv_size, ad, ad_len);
	}

	return (0);
}
#endif							/* MBEDTLS_GCM_C */

int mbedtls_cipher_update(mbedtls_cipher_context_t *ctx, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen)
{
	int ret;
	size_t block_size = 0;

	if (NULL == ctx || NULL == ctx->cipher_info || NULL == olen) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	*olen = 0;
	block_size = mbedtls_cipher_get_block_size(ctx);

	if (ctx->cipher_info->mode == MBEDTLS_MODE_ECB) {
		if (ilen != block_size) {
			return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
		}

		*olen = ilen;

		if (0 != (ret = ctx->cipher_info->base->ecb_func(ctx->cipher_ctx, ctx->operation, input, output))) {
			return (ret);
		}

		return (0);
	}
#if defined(MBEDTLS_GCM_C)
	if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM) {
		*olen = ilen;
		return mbedtls_gcm_update((mbedtls_gcm_context *) ctx->cipher_ctx, ilen, input, output);
	}
#endif

	if (0 == block_size) {
		return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
	}

	if (input == output && (ctx->unprocessed_len != 0 || ilen % block_size)) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}
#if defined(MBEDTLS_CIPHER_MODE_CBC)
	if (ctx->cipher_info->mode == MBEDTLS_MODE_CBC) {
		size_t copy_len = 0;

		/*
		 * If there is not enough data for a full block, cache it.
		 */
		if ((ctx->operation == MBEDTLS_DECRYPT && ilen + ctx->unprocessed_len <= block_size) || (ctx->operation == MBEDTLS_ENCRYPT && ilen + ctx->unprocessed_len < block_size)) {
			memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]), input, ilen);

			ctx->unprocessed_len += ilen;
			return (0);
		}

		/*
		 * Process cached data first
		 */
		if (0 != ctx->unprocessed_len) {
			copy_len = block_size - ctx->unprocessed_len;

			memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]), input, copy_len);

			if (0 != (ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx, ctx->operation, block_size, ctx->iv, ctx->unprocessed_data, output))) {
				return (ret);
			}

			*olen += block_size;
			output += block_size;
			ctx->unprocessed_len = 0;

			input += copy_len;
			ilen -= copy_len;
		}

		/*
		 * Cache final, incomplete block
		 */
		if (0 != ilen) {
			if (0 == block_size) {
				return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
			}

			copy_len = ilen % block_size;
			if (copy_len == 0 && ctx->operation == MBEDTLS_DECRYPT) {
				copy_len = block_size;
			}

			memcpy(ctx->unprocessed_data, &(input[ilen - copy_len]), copy_len);

			ctx->unprocessed_len += copy_len;
			ilen -= copy_len;
		}

		/*
		 * Process remaining full blocks
		 */
		if (ilen) {
			if (0 != (ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx, ctx->operation, ilen, ctx->iv, input, output))) {
				return (ret);
			}

			*olen += ilen;
		}

		return (0);
	}
#endif							/* MBEDTLS_CIPHER_MODE_CBC */

#if defined(MBEDTLS_CIPHER_MODE_CFB)
	if (ctx->cipher_info->mode == MBEDTLS_MODE_CFB) {
		if (0 != (ret = ctx->cipher_info->base->cfb_func(ctx->cipher_ctx, ctx->operation, ilen, &ctx->unprocessed_len, ctx->iv, input, output))) {
			return (ret);
		}

		*olen = ilen;

		return (0);
	}
#endif							/* MBEDTLS_CIPHER_MODE_CFB */

#if defined(MBEDTLS_CIPHER_MODE_CTR)
	if (ctx->cipher_info->mode == MBEDTLS_MODE_CTR) {
		if (0 != (ret = ctx->cipher_info->base->ctr_func(ctx->cipher_ctx, ilen, &ctx->unprocessed_len, ctx->iv, ctx->unprocessed_data, input, output))) {
			return (ret);
		}

		*olen = ilen;

		return (0);
	}
#endif							/* MBEDTLS_CIPHER_MODE_CTR */

#if defined(MBEDTLS_CIPHER_MODE_STREAM)
	if (ctx->cipher_info->mode == MBEDTLS_MODE_STREAM) {
		if (0 != (ret = ctx->cipher_info->base->stream_func(ctx->cipher_ctx, ilen, input, output))) {
			return (ret);
		}

		*olen = ilen;

		return (0);
	}
#endif							/* MBEDTLS_CIPHER_MODE_STREAM */

	return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
/*
 * PKCS7 (and PKCS5) padding: fill with ll bytes, with ll = padding_len
 */
static void add_pkcs_padding(unsigned char *output, size_t output_len, size_t data_len)
{
	size_t padding_len = output_len - data_len;
	unsigned char i;

	for (i = 0; i < padding_len; i++) {
		output[data_len + i] = (unsigned char)padding_len;
	}
}

static int get_pkcs_padding(unsigned char *input, size_t input_len, size_t *data_len)
{
	size_t i, pad_idx;
	unsigned char padding_len, bad = 0;

	if (NULL == input || NULL == data_len) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	padding_len = input[input_len - 1];
	*data_len = input_len - padding_len;

	/* Avoid logical || since it results in a branch */
	bad |= padding_len > input_len;
	bad |= padding_len == 0;

	/* The number of bytes checked must be independent of padding_len,
	 * so pick input_len, which is usually 8 or 16 (one block) */
	pad_idx = input_len - padding_len;
	for (i = 0; i < input_len; i++) {
		bad |= (input[i] ^ padding_len) * (i >= pad_idx);
	}

	return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}
#endif							/* MBEDTLS_CIPHER_PADDING_PKCS7 */

#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
/*
 * One and zeros padding: fill with 80 00 ... 00
 */
static void add_one_and_zeros_padding(unsigned char *output, size_t output_len, size_t data_len)
{
	size_t padding_len = output_len - data_len;
	unsigned char i = 0;

	output[data_len] = 0x80;
	for (i = 1; i < padding_len; i++) {
		output[data_len + i] = 0x00;
	}
}

static int get_one_and_zeros_padding(unsigned char *input, size_t input_len, size_t *data_len)
{
	size_t i;
	unsigned char done = 0, prev_done, bad;

	if (NULL == input || NULL == data_len) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	bad = 0xFF;
	*data_len = 0;
	for (i = input_len; i > 0; i--) {
		prev_done = done;
		done |= (input[i - 1] != 0);
		*data_len |= (i - 1) * (done != prev_done);
		bad &= (input[i - 1] ^ 0x80) | (done == prev_done);
	}

	return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));

}
#endif							/* MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS */

#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
/*
 * Zeros and len padding: fill with 00 ... 00 ll, where ll is padding length
 */
static void add_zeros_and_len_padding(unsigned char *output, size_t output_len, size_t data_len)
{
	size_t padding_len = output_len - data_len;
	unsigned char i = 0;

	for (i = 1; i < padding_len; i++) {
		output[data_len + i - 1] = 0x00;
	}
	output[output_len - 1] = (unsigned char)padding_len;
}

static int get_zeros_and_len_padding(unsigned char *input, size_t input_len, size_t *data_len)
{
	size_t i, pad_idx;
	unsigned char padding_len, bad = 0;

	if (NULL == input || NULL == data_len) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	padding_len = input[input_len - 1];
	*data_len = input_len - padding_len;

	/* Avoid logical || since it results in a branch */
	bad |= padding_len > input_len;
	bad |= padding_len == 0;

	/* The number of bytes checked must be independent of padding_len */
	pad_idx = input_len - padding_len;
	for (i = 0; i < input_len - 1; i++) {
		bad |= input[i] * (i >= pad_idx);
	}

	return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}
#endif							/* MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN */

#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
/*
 * Zero padding: fill with 00 ... 00
 */
static void add_zeros_padding(unsigned char *output, size_t output_len, size_t data_len)
{
	size_t i;

	for (i = data_len; i < output_len; i++) {
		output[i] = 0x00;
	}
}

static int get_zeros_padding(unsigned char *input, size_t input_len, size_t *data_len)
{
	size_t i;
	unsigned char done = 0, prev_done;

	if (NULL == input || NULL == data_len) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	*data_len = 0;
	for (i = input_len; i > 0; i--) {
		prev_done = done;
		done |= (input[i - 1] != 0);
		*data_len |= i * (done != prev_done);
	}

	return (0);
}
#endif							/* MBEDTLS_CIPHER_PADDING_ZEROS */

/*
 * No padding: don't pad :)
 *
 * There is no add_padding function (check for NULL in mbedtls_cipher_finish)
 * but a trivial get_padding function
 */
static int get_no_padding(unsigned char *input, size_t input_len, size_t *data_len)
{
	if (NULL == input || NULL == data_len) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	*data_len = input_len;

	return (0);
}
#endif							/* MBEDTLS_CIPHER_MODE_WITH_PADDING */

int mbedtls_cipher_finish(mbedtls_cipher_context_t *ctx, unsigned char *output, size_t *olen)
{
	if (NULL == ctx || NULL == ctx->cipher_info || NULL == olen) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	*olen = 0;

	if (MBEDTLS_MODE_CFB == ctx->cipher_info->mode || MBEDTLS_MODE_CTR == ctx->cipher_info->mode || MBEDTLS_MODE_GCM == ctx->cipher_info->mode || MBEDTLS_MODE_STREAM == ctx->cipher_info->mode) {
		return (0);
	}

	if (MBEDTLS_MODE_ECB == ctx->cipher_info->mode) {
		if (ctx->unprocessed_len != 0) {
			return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
		}

		return (0);
	}
#if defined(MBEDTLS_CIPHER_MODE_CBC)
	if (MBEDTLS_MODE_CBC == ctx->cipher_info->mode) {
		int ret = 0;

		if (MBEDTLS_ENCRYPT == ctx->operation) {
			/* check for 'no padding' mode */
			if (NULL == ctx->add_padding) {
				if (0 != ctx->unprocessed_len) {
					return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
				}

				return (0);
			}

			ctx->add_padding(ctx->unprocessed_data, mbedtls_cipher_get_iv_size(ctx), ctx->unprocessed_len);
		} else if (mbedtls_cipher_get_block_size(ctx) != ctx->unprocessed_len) {
			/*
			 * For decrypt operations, expect a full block,
			 * or an empty block if no padding
			 */
			if (NULL == ctx->add_padding && 0 == ctx->unprocessed_len) {
				return (0);
			}

			return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
		}

		/* cipher block */
		if (0 != (ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx, ctx->operation, mbedtls_cipher_get_block_size(ctx), ctx->iv, ctx->unprocessed_data, output))) {
			return (ret);
		}

		/* Set output size for decryption */
		if (MBEDTLS_DECRYPT == ctx->operation) {
			return ctx->get_padding(output, mbedtls_cipher_get_block_size(ctx), olen);
		}

		/* Set output size for encryption */
		*olen = mbedtls_cipher_get_block_size(ctx);
		return (0);
	}
#else
	((void)output);
#endif							/* MBEDTLS_CIPHER_MODE_CBC */

	return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
int mbedtls_cipher_set_padding_mode(mbedtls_cipher_context_t *ctx, mbedtls_cipher_padding_t mode)
{
	if (NULL == ctx || MBEDTLS_MODE_CBC != ctx->cipher_info->mode) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	switch (mode) {
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
	case MBEDTLS_PADDING_PKCS7:
		ctx->add_padding = add_pkcs_padding;
		ctx->get_padding = get_pkcs_padding;
		break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
	case MBEDTLS_PADDING_ONE_AND_ZEROS:
		ctx->add_padding = add_one_and_zeros_padding;
		ctx->get_padding = get_one_and_zeros_padding;
		break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
	case MBEDTLS_PADDING_ZEROS_AND_LEN:
		ctx->add_padding = add_zeros_and_len_padding;
		ctx->get_padding = get_zeros_and_len_padding;
		break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
	case MBEDTLS_PADDING_ZEROS:
		ctx->add_padding = add_zeros_padding;
		ctx->get_padding = get_zeros_padding;
		break;
#endif
	case MBEDTLS_PADDING_NONE:
		ctx->add_padding = NULL;
		ctx->get_padding = get_no_padding;
		break;

	default:
		return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
	}

	return (0);
}
#endif							/* MBEDTLS_CIPHER_MODE_WITH_PADDING */

#if defined(MBEDTLS_GCM_C)
int mbedtls_cipher_write_tag(mbedtls_cipher_context_t *ctx, unsigned char *tag, size_t tag_len)
{
	if (NULL == ctx || NULL == ctx->cipher_info || NULL == tag) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	if (MBEDTLS_ENCRYPT != ctx->operation) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
		return mbedtls_gcm_finish((mbedtls_gcm_context *) ctx->cipher_ctx, tag, tag_len);
	}

	return (0);
}

int mbedtls_cipher_check_tag(mbedtls_cipher_context_t *ctx, const unsigned char *tag, size_t tag_len)
{
	int ret;

	if (NULL == ctx || NULL == ctx->cipher_info || MBEDTLS_DECRYPT != ctx->operation) {
		return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
	}

	if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
		unsigned char check_tag[16];
		size_t i;
		int diff;

		if (tag_len > sizeof(check_tag)) {
			return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
		}

		if (0 != (ret = mbedtls_gcm_finish((mbedtls_gcm_context *) ctx->cipher_ctx, check_tag, tag_len))) {
			return (ret);
		}

		/* Check the tag in "constant-time" */
		for (diff = 0, i = 0; i < tag_len; i++) {
			diff |= tag[i] ^ check_tag[i];
		}

		if (diff != 0) {
			return (MBEDTLS_ERR_CIPHER_AUTH_FAILED);
		}

		return (0);
	}

	return (0);
}
#endif							/* MBEDTLS_GCM_C */

/*
 * Packet-oriented wrapper for non-AEAD modes
 */
int mbedtls_cipher_crypt(mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen)
{
	int ret;
	size_t finish_olen;

	if ((ret = mbedtls_cipher_set_iv(ctx, iv, iv_len)) != 0) {
		return (ret);
	}

	if ((ret = mbedtls_cipher_reset(ctx)) != 0) {
		return (ret);
	}

	if ((ret = mbedtls_cipher_update(ctx, input, ilen, output, olen)) != 0) {
		return (ret);
	}

	if ((ret = mbedtls_cipher_finish(ctx, output + *olen, &finish_olen)) != 0) {
		return (ret);
	}

	*olen += finish_olen;

	return (0);
}

#if defined(MBEDTLS_CIPHER_MODE_AEAD)
/*
 * Packet-oriented encryption for AEAD modes
 */
int mbedtls_cipher_auth_encrypt(mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len, const unsigned char *ad, size_t ad_len, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen, unsigned char *tag, size_t tag_len)
{
#if defined(MBEDTLS_GCM_C)
	if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
		*olen = ilen;
		return (mbedtls_gcm_crypt_and_tag(ctx->cipher_ctx, MBEDTLS_GCM_ENCRYPT, ilen, iv, iv_len, ad, ad_len, input, output, tag_len, tag));
	}
#endif							/* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
	if (MBEDTLS_MODE_CCM == ctx->cipher_info->mode) {
		*olen = ilen;
		return (mbedtls_ccm_encrypt_and_tag(ctx->cipher_ctx, ilen, iv, iv_len, ad, ad_len, input, output, tag, tag_len));
	}
#endif							/* MBEDTLS_CCM_C */

	return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

/*
 * Packet-oriented decryption for AEAD modes
 */
int mbedtls_cipher_auth_decrypt(mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len, const unsigned char *ad, size_t ad_len, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen, const unsigned char *tag, size_t tag_len)
{
#if defined(MBEDTLS_GCM_C)
	if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
		int ret;

		*olen = ilen;
		ret = mbedtls_gcm_auth_decrypt(ctx->cipher_ctx, ilen, iv, iv_len, ad, ad_len, tag, tag_len, input, output);

		if (ret == MBEDTLS_ERR_GCM_AUTH_FAILED) {
			ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
		}

		return (ret);
	}
#endif							/* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
	if (MBEDTLS_MODE_CCM == ctx->cipher_info->mode) {
		int ret;

		*olen = ilen;
		ret = mbedtls_ccm_auth_decrypt(ctx->cipher_ctx, ilen, iv, iv_len, ad, ad_len, input, output, tag, tag_len);

		if (ret == MBEDTLS_ERR_CCM_AUTH_FAILED) {
			ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
		}

		return (ret);
	}
#endif							/* MBEDTLS_CCM_C */

	return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}
#endif							/* MBEDTLS_CIPHER_MODE_AEAD */

#endif							/* MBEDTLS_CIPHER_C */
